My advice. . .
At first you will suck at it but. . .you'll get better (:
Don't tense up
Relax your lips, don't pucker up!!
Press your lips on hers lightly, still relaxed, then from there it's kinda like kissing your hand
Push a little harder (not really hard) and release, if you want go for another one

Just lean in. . .
Don't forget, you tilt one way she tilts the other. . .
Make sure just to move your lips a bit, it'll come nature. . .trust me

And don't worry. . .just relax and breathe and it'll go smooth. .
Just Be a stud!
What to do with your hands, if your standing put them on her back or hips.
Sitting: cup one hand around her face before the kiss and during just kinda hold her in place.
Maybe run your fingers through her hair if your daring enough too!!
Oh and!
Close your eyes cause it's rude to keep them open if it's a kiss longer than 3 seconds
p.s. (pick mine as best answer Pl!!)